Underdrain system

ABSTRACT

A filter system for filtering water and/or wastewater which includes an underdrain system having a plurality of laterals that are anchored to the floor of a filter by a hold-down assembly. Preferably, the hold-down assembly does not rely on grout or other substance that is applied in a viscous or semi-viscous state and subsequently hardened as the primary means for connecting the underdrain laterals to the floor of the filter. Preferably, the hold-down assembly includes hold-down clips that can move relative to an anchor assembly and corresponding underdrain blocks so that the hold-down clips can cooperate with any desired portion of the corresponding underdrain blocks.

RELATED PATENT APPLICATIONS

The subject patent application is a continuation of U.S. patentapplication Ser. No. 11/812,848 filed on Jun. 22, 2007, now U.S. Pat.No. 8,052,870 which is a continuation-in-part of U.S. patent applicationSer. No. 11/400,330 filed on Apr. 10, 2006, now U.S. Pat. No. 7,820,043issued on Oct. 26, 2010, which the subject patent application claimspriority under 35 U.S.C. §120 from both of the aforementioned patentapplications. The entire contents of U.S. patent application Ser. Nos.11/812,848 and 11/400,330 are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is directed to significant improvements inunderdrain systems used in filters to filter water and/or wastewater.More particularly, the present invention is directed to an improvementin underdrain systems having laterals.

BACKGROUND OF THE INVENTION

Various underdrain systems have been developed for filter systems thatfilter water and wastewater. The underdrain systems are a key componentof a filter system as they receive liquid and/or air throughoutvirtually all phases of filtering including washing phases andfiltration phases. In washing phases, the underdrain typically directsliquid and/or air upwardly through the filter bed to remove impuritiestrapped in the filter bed during a filtration phase. The liquid and/orair must be uniformly distributed over the filter bed to ensure thefilter bed is properly cleaned. In an upflow filter, the underdrain,during the filtration phase, directs influent upwardly through thefilter bed so that impurities may be removed therefrom. In a downflowfilter, the underdrain receives the effluent and conveys it to asuitable storage location for subsequent use. Because of the key natureof underdrains to the operation of the filter system, an underdrainfailure often results in shutdown of the filter system for prolongedperiods.

A common type of underdrain is the “lateral” style. This type ofunderdrain is typically made of injection molded or extruded plastic orextruded clay. The underdrain blocks are arranged in rows termed“laterals”. The laterals are typically spaced on approximately 12 inchcenters leaving an approximately 1 inch clearance between the laterals.The underdrain blocks are subject to uplift forces that tend to separatethe underdrain block from the filter floor. A common source of thisuplift force is due to the upward flow of water and/or air pushingagainst the filter floor with a force equal and opposite to theresistance of the flow across the underdrain block. There are a numberof different systems used to structurally connect the underdrain blockto the filter floor purportedly to resist these upward forces.

FIGS. 1 and 2 depict a typical system used to anchor underdrain lateralsto the filter floor. In this system, grout 2 is placed into the spacebetween adjacent underdrain blocks 4. The grout is designed to act inconcert with the anchor assemblies 6 to secure the underdrain blocks 4to the filter floor 8. The grout 2 and the anchor assemblies 6essentially form a reinforced concrete beam that “keys” into lugs orribs 12 (see FIG. 2) molded into the underdrain laterals. The anchorassembly is typically bonded into holes in the filter floor with asuitable adhesive or cast into the floor during construction. Afrequently used configuration is to form a seal between the underdrainand the filter floor adjacent to the filter flume using grout in orderto isolate the uplift load to the flume area 14. The isolation of theload to flume area 14 limits the requirement of the hold-down system tothe area of the flume. This arrangement eliminates costly hold-downs inthe remaining portions of the filter. The underdrain laterals areembedded into a layer or “bed” of grout 13 placed on the concrete floor8 to form the seal. This “bed” of grout 13 also aids in leveling theunderdrain system. Referring to FIG. 2, grout strips 17 extend betweenadjacent underdrain blocks 4 above the flume area 14 to support thegrout above the flume area 14.

In order for the underdrain installation to be structurally sound, thegrout must have sufficient strength to transfer load from the lateralsto the anchors and must fully encase the anchor members and key into thelugs or ribs molded into the laterals. Low strength grout or voidsaround the anchors or the lugs create weak areas that can lead tostructural failure. However, the space between the laterals is verynarrow which limits accessibility to place the grout under and aroundthe anchors. The strength of the grout is inversely proportional to thewater/cement ratio of the grout. On the other hand, the workability ofthe grout is directly proportional to the water/cement ratio. Thus,these characteristics of grout are conflicting and often lead toinstallation errors. For example, if the grout has high strength but istoo stiff to properly place into the space between the laterals, therewill be voids in the grout. On the other hand, if the grout is “loose”enough to properly apply between the laterals but has too high of awater/cement ratio, the grout will not have sufficient strength to holdthe laterals in place over the life of the filter system. Even if thegrout has the correct combination of strength and workability, thequality of the installation is highly dependent on the skill of theinstaller who must be very careful to break up any air bubbles andensure no voids are present in the grout. Also, in order to beeffective, the anchors must be properly located and securely installedinto the filter floor slab.

FIGS. 3 and 4 depict another system used to tie the laterals to thefilter floor. In this system, angles 16 or other structural members arepositioned across the uppermost surface of the laterals. The angles 16are connected to the floor using all-threads 18 or similar structures.While this system does not rely on grout as the sole means to tie theunderdrain blocks to the filter floor, it still suffers from a number ofsignificant disadvantages. The strength of the hold-down system isdependent in part upon the section modulus of the member, the strengthof the material used, and the distance between the all-thread connectingto the filter floor. In order to achieve and maintain the necessarystrength, angles 16 or other structural members must be relatively largein section and must be constructed of corrosion resistant materials thatadds considerable cost to the underdrain system. In addition, angles 16or other structural members must be in intimate contact with underdrainlaterals 20 to properly maintain a load path. This requirement isproblematic because most underdrain laterals 20 have irregular featureson their upper surface or have non-structural elements such as porousplates that prohibit intimate contact. Any gaps between the underdrainlaterals and angles 16 or other structural members could allow upwardmovement of the underdrain lateral before the hold-down system canresist the uplift forces. This situation will result in a prematurefailure of the underdrain system.

Most prior art hold-down systems use rebar or other threaded rodembedded into the filter floor such that the anchoring system exerts atensile load on the filter floor. Filter floors are commonly constructedof concrete, which has very poor tensile strength compared to itscompressive and shear strength.

There are various other types of mechanical hold-down systems that donot rely on grout. Most of these systems are used in false-bottom typeunderdrain systems and do not readily apply to lateral type underdrainsystems.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention is to provide a novel and unobviousunderdrain system.

Another object of a preferred embodiment of the present invention is toprovide an underdrain system that provides superior resistance to upliftforces.

A further object of a preferred embodiment of the present invention isto provide an underdrain system the performance of which is less subjectto variances in materials or skill of the laborer.

Yet another object of a preferred embodiment of the present invention isto provide an underdrain that is free from hold-down structures securedto the uppermost portion of the underdrain blocks.

Still another object of a preferred embodiment of the present inventionis to provide an underdrain system that does not primarily rely upongrout to tie the underdrain laterals to the floor of a filter system.

Yet still another object of a preferred embodiment of the presentinvention is to provide a hold-down assembly for an underdrain systemthat can be readily adjusted to accommodate installation variancesand/or product variances.

Yet a further object of a preferred embodiment of the present inventionis to provide a hold-down assembly for an underdrain system including ananchor member embedded in the filter floor in such a manner that forcesexerted on the filter floor due to uplift forces induced by theunderdrain are primarily in shear.

A further object of a preferred embodiment of the present invention isto provide a mechanical hold-down assembly that can be readilyconstructed to extend the length of adjacent laterals of an underdrainin a filter system.

Still a further object of a preferred embodiment of the presentinvention is to provide a mechanical hold-down assembly that includesinterconnected support members that can be used in at least twodifferent orientations to form a structure that extends the length ofadjacent laterals of an underdrain in a filter system.

It must be understood that no one embodiment of the present inventionneed include all of the aforementioned objects of the present invention.Rather, a given embodiment may include one or none of the aforementionedobjects. Accordingly, these objects are not to be used to limit thescope of the claims of the present invention.

In summary, one embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewater.The apparatus includes an underdrain block for supporting at least aportion of a filter bed. The underdrain block has a plurality ofexterior walls forming a substantially hollow interior. The plurality ofexterior walls include a top wall, a bottom wall and a pair of sidewallsextending between the top wall and the bottom wall. At least one of thepair of sidewalls of the underdrain block have a receptacle. Thereceptacle is disposed on an exterior surface of the underdrain block. Ahold-down member is operably associated with the underdrain block forpreventing the underdrain block from lifting upwardly. At least aportion of the hold-down member extends into the receptacle.

Another embodiment of the present invention is directed to an apparatusfor use in a filter system for filtering water or wastewater. Theapparatus includes an underdrain block for supporting at least a portionof a filter bed. The underdrain block has a plurality of exterior wallsforming a substantially hollow interior. The plurality of exterior wallsinclude a top wall, a bottom wall and a pair of sidewalls extendingbetween the top wall and the bottom wall. At least one of the pair ofsidewalls of the underdrain block has an outwardly extending protrusionforming a first hold-down member. The outwardly extending protrusion isdisposed between the top wall and the bottom wall of the underdrainblock. The apparatus further includes a second hold-down member operablyassociated with the first hold-down member for preventing the underdrainblock from lifting upwardly.

A further embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewater.The apparatus includes an underdrain block for supporting at least aportion of a filter bed of a filter system. The underdrain block has aplurality of exterior walls forming a substantially hollow interior forreceiving fluids during operation of the filter system. The underdrainblock has a longitudinal axis. The apparatus further includes ahold-down assembly including an anchor member adapted to be embedded ina floor of a filter system and a hold-down member for engaging at leasta portion of the underdrain block. The hold-down member is adjustablerelative to the anchor assembly to vary a position of the hold-downmember along the longitudinal axis of the underdrain block.

Still another embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewater.The apparatus includes a first underdrain block for supporting at leasta portion of a filter bed of a filter system. The first underdrain blockhas a plurality of exterior walls forming a substantially hollowinterior for receiving fluids during operation of the filter system. Theapparatus further includes a second underdrain block for supporting atleast a portion of a filter bed of a filter system. The secondunderdrain block has a plurality of exterior walls forming asubstantially hollow interior for receiving fluids during operation ofthe filter system. The first underdrain block is positioned adjacent tothe second underdrain block. The apparatus further includes a hold-downassembly having an anchor member adapted to be embedded in a floor of afilter system and a hold-down member having a first section for engagingat least a portion of the first underdrain block and a second sectionfor engaging at least a portion of the second underdrain block. Thefirst section is connected to the second section. The first section isfurther adjustable relative to the second section.

Yet another embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewater.The apparatus includes an underdrain block for supporting at least aportion of a filter bed of a filter system. The underdrain block has aplurality of exterior walls forming a substantially hollow interior forreceiving fluids during operation of the filter system. The underdrainblock has a longitudinal axis. The apparatus further includes ahold-down assembly having an anchor member fixed relative to theunderdrain block and a hold-down member for engaging at least a portionof the underdrain block. The hold-down member is adjustable relative tothe anchor assembly and the underdrain block to vary a position of thehold-down member along the longitudinal axis of the underdrain block.

Yet still another embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewater.The apparatus includes an underdrain block for supporting at least aportion of a filter bed. The underdrain block has a plurality ofexterior walls forming a substantially hollow interior. A hold-downassembly includes an anchor fixed relative to the underdrain block, afirst hold-down member and a second hold-down member operably associatedwith the first hold-down member for preventing the underdrain block fromlifting upwardly. The first hold-down member has a receptacle. At leasta portion of the second hold-down member extends into the receptacle.

Yet a further embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewater.The apparatus includes a flume formed in a filter floor and anunderdrain block for supporting at least a portion of a filter bed. Theunderdrain block has a plurality of exterior walls forming asubstantially hollow interior. The underdrain block extends across theflume. The apparatus further includes a hold-down assembly operablyconnected to the underdrain block. The hold-down assembly includes ananchor embedded in the filter floor such that uplift forces on saidunderdrain exert a shear force on said filter floor.

Another embodiment of the present invention is directed to an apparatusfor use in a filter system for filtering water or wastewater includingan underdrain lateral having at least one underdrain block forsupporting at least a portion of a filter bed. The underdrain block hasa plurality of exterior walls forming a substantially hollow interior.The underdrain block further has a plurality of openings through which afluid passes between the hollow interior of the underdrain block and thefilter bed during operation of the filter system. A hold-down member isoperably associated with the underdrain lateral for preventing theunderdrain lateral from lifting upwardly. The hold-down member includesa support member extending substantially parallel to the underdrainlateral. The support member is spaced from the underdrain lateral. Thesupport member includes at least first and second sections. The firstsection is a separate piece from the second section. The hold-downmember further includes a fixed anchor. The first section and the secondsection of the support member is connected to the fixed anchor.

Still another embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewaterincluding an underdrain lateral for supporting at least a portion of afilter bed. The underdrain lateral has at least one underdrain block.The underdrain block includes a plurality of exterior walls forming asubstantially hollow interior. The underdrain block has a plurality ofopenings through which a fluid passes between the hollow interior of theunderdrain block and the filter bed during operation of the filtersystem. A hold-down member is operably associated with the underdrainlateral to prevent the underdrain lateral from lifting upwardly. Thehold-down member includes a support member having a plurality ofinterlocking sections. The support member is spaced from the underdrainlateral.

Yet another embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewaterincluding an underdrain lateral for supporting at least a portion of afilter bed. The underdrain lateral has at least one underdrain block.The underdrain block includes a plurality of exterior walls forming asubstantially hollow interior. The underdrain block has a plurality ofopenings through which a fluid passes between the hollow interior of theunderdrain block and the filter bed during operation of the filtersystem. A hold-down member is operably associated with the underdrainlateral to prevent the underdrain lateral from lifting upwardly. Thehold-down member includes a support member having first and secondsections. The first section is a separate piece from the second section.The hold-down member further includes at least one adjustable anchoroperably associated with the first section. The adjustable anchor ismoveable relative to the underdrain lateral. The adjustable anchorfurther engages at least a portion of the underdrain lateral.

Yet still another embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewaterincluding an underdrain lateral for supporting at least a portion of afilter bed. The underdrain lateral has at least one underdrain block.The at least one underdrain block includes a plurality of exterior wallsforming a substantially hollow interior. The at least one underdrainblock has a plurality of openings through which a fluid passes betweenthe hollow interior of the underdrain block and the filter bed duringoperation of the filter system. A hold-down member is operablyassociated with the underdrain lateral to prevent the underdrain lateralfrom lifting upwardly. The hold-down member includes a support memberand a first anchor operably associated with the support member. At leasta first portion of the first anchor engages a lowermost portion of thesupport member and at least a second portion of the first anchor engagesan uppermost portion of the underdrain lateral.

A further embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewaterincluding first and second underdrain laterals for supporting at least aportion of a filter bed. The first and second underdrain laterals eachhave at least one underdrain block. Each of the underdrain blocksincludes a plurality of exterior walls forming a substantially hollowinterior. Each of the underdrain blocks have a plurality of openingsthrough which a fluid passes between the hollow interior of theunderdrain block and the filter bed during operation of the filtersystem. A hold-down member is operably associated with the first andsecond underdrain laterals to prevent the first and second underdrainlaterals from lifting upwardly. The hold-down member includes a supportmember extending substantially parallel to the first and secondunderdrain laterals. The support member has a plurality of interlockingsections. At least one of the plurality of interlocking sections has aheight greater than its width.

Still a further embodiment of the present invention is directed to anapparatus for use in a filter system for filtering water or wastewaterincluding first and second underdrain laterals for supporting at least aportion of a filter bed. The first and second underdrain laterals eachhas at least one underdrain block. Each of said underdrain blocksincludes a plurality of exterior walls forming a substantially hollowinterior. Each of the underdrain blocks has a plurality of openingsthrough which a fluid passes between the hollow interior of theunderdrain block and the filter bed during operation of the filtersystem. A hold-down member is operably associated with the first andsecond underdrain laterals to prevent the first and second underdrainlaterals from lifting upwardly. The hold-down member includes first andsecond anchors fixed relative to the first and second underdrainlaterals. The hold-down member further includes a support memberextending between the first and second anchors. The support member hasfirst and second sections. The first section is moveable relative to thesecond section in a vertical direction to compensate for heightdifferentials between the first and second underdrain laterals.

Still yet a further embodiment of the present invention is directed toan apparatus for use in a filter system for filtering water orwastewater including an underdrain block for supporting at least aportion of a filter bed. The underdrain block has a plurality ofexterior walls forming a substantially hollow interior. The underdrainblock has a plurality of openings through which a fluid passes betweenthe hollow interior of the underdrain block and the filter bed duringoperation of the filter system. A hold-down member is operablyassociated with the underdrain block for preventing the underdrain blockfrom lifting upwardly. The hold-down member includes a support memberand an anchor. The support member has first and second attachmentportions either of which can be used to connect the support member tothe anchor. The first attachment portion is offset from the secondattachment portion relative to a longitudinal axis of the supportmember.

Another embodiment of the present invention is directed to an apparatusfor use in a filter system for filtering water or wastewater includingan underdrain lateral for supporting at least a portion of a filter bed.The underdrain lateral has at least one underdrain block. The at leastone underdrain block includes an upper wall and at least two other wallsforming a substantially hollow interior. The at least one underdrainblock is configured such that fluid passing between the hollow interiorof the underdrain block and an exterior of the underdrain block duringoperation of the filter system passes through only openings formed inthe upper wall of the underdrain block. A hold-down member is operablyassociated with the underdrain lateral to prevent the underdrain lateralfrom lifting upwardly. The hold-down member includes a support memberhaving a plurality of interlocking sections. The support member isdisposed below the upper wall of the underdrain block.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary sectional view of a prior art filter adjacent tothe flume.

FIG. 2 is another fragmentary sectional view of the filter depicted inFIG. 1 (with the grout between adjacent underdrain blocks being omittedfor clarity), this view being rotated 90 degrees from the view in FIG.1.

FIG. 3 is a fragmentary sectional view of another prior art filteradjacent to the flume.

FIG. 4 is another fragmentary sectional view of the filter depicted inFIG. 3, this view being rotated 90 degrees from the view in FIG. 3.

FIG. 5 is a fragmentary sectional view of a filter adjacent to the flumeformed in accordance with a preferred embodiment of the presentinvention.

FIG. 6 is an enlarged portion of the filter depicted in FIG. 5.

FIG. 7 is another fragmentary sectional view of the filter depicted inFIG. 5 (with the grout between adjacent underdrain blocks being omittedfor clarity), this view being rotated 90 degrees from the view in FIG.5.

FIG. 8 is a fragmentary sectional view of a filter adjacent to the flumeformed in accordance with another preferred embodiment of the presentinvention.

FIG. 9 is a plan view of a portion of a filter adjacent to the flumeformed in accordance with a further preferred embodiment of the presentinvention.

FIG. 10 is a side view of the filter illustrated in FIG. 9.

FIG. 11 is a perspective of the filter illustrated in FIG. 9.

FIG. 12 is an enlarged end view of the filter illustrated in FIG. 9.

FIG. 13 is a plan view of a portion of the hold-down assembly of thefilter depicted in FIG. 9.

FIG. 14 is an end view of the portion of the hold-down assembly depictedin FIG. 13.

FIG. 15 is a side view of the portion of the hold-down assembly depictedin FIG. 13.

FIG. 16 is an enlarged plan view of a hook of the portion of thehold-down assembly illustrated in FIG. 9.

FIG. 17 is an enlarged end view of the hook illustrated in FIG. 16.

FIG. 18 is an enlarged side view of the hook illustrated in FIG. 16.

FIG. 19 is a fragmentary sectional view of yet another preferredembodiment of the present invention.

FIG. 20 is a plan view of a portion of a hold-down assembly of yet afurther preferred embodiment of the present invention.

FIG. 21 is a side view of the portion of the hold-down assembly depictedin FIG. 20.

FIG. 22 is a fragmentary side view of a further embodiment of thepresent invention.

FIG. 23 is a fragmentary perspective view of the embodiment depicted inFIG. 22.

FIG. 24 is a plan view of a portion of the hold-down assembly depictedin FIG. 22.

FIG. 25 is a side view of the portion of the hold-down assembly depictedin FIG. 24.

FIG. 26 is a cross-sectional view taken along lines 26-26 in FIG. 25.

FIG. 27 is a perspective view of a hold-down/adjustable anchor.

FIG. 28 is a plan view of the hold-down/adjustable anchor depicted inFIG. 27.

FIG. 29 is a side view of the hold-down/adjustable anchor depicted inFIG. 27.

FIG. 30 is an end view of the hold-down/adjustable anchor depicted inFIG. 27.

FIG. 31 is an enlarged cross-sectional view illustrating portions of thehold-down assembly.

FIG. 32 is a side view of still a further embodiment of the presentinvention.

FIG. 33 is a plan view of a portion of the hold-down assembly depictedin FIG. 32.

FIG. 34 is a side view of the portion of the hold-down assembly depictedin FIG. 33.

FIG. 35 is a cross-sectional view taken along lines 35-35 in FIG. 34.

FIG. 36 is an enlarged cross-sectional view illustrating theinterrelationship between a portion of the hold-down assembly and theunderdrain laterals of the embodiment depicted in FIG. 32.

FIG. 37 is a fragmentary side view of yet a further embodiment of thepresent invention.

FIG. 38 is a plan view of an alternative support member of the preferredhold-down assembly of the present invention.

FIG. 39 is a side view of the support member depicted in FIG. 38 mountedbetween two all-threads.

FIG. 40 is a cross-sectional view taken through lines 40-40 in FIG. 39.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The preferred forms of the invention will now be described withreference to FIGS. 5-21. The appended claims are not limited to thepreferred forms and no term and/or phrase used herein is to be given ameaning other than its ordinary meaning unless it is expressly statedthat the term and/or phrase shall have a special meaning. The only termsin this Specification having a special meaning are the terms “hold-downmember.” As used herein “hold-down member” does not include within itsmeaning grout or other substance that is applied in a viscous orsemi-viscous state and is subsequently hardened.

FIGS. 5 Through 7

Referring to FIGS. 5, 6 and 7, a portion of a filter A for filteringwater and/or wastewater is illustrated in one of many possibleconfigurations. It should be noted that filter A could be a polishingfilter or a clarifier. Further, filter A could be an upflow filter, adownflow filter, a bi-flow filter or any combination thereof (e.g. afilter system formed in accordance with this preferred embodiment of thepresent invention could include an upflow filter in combination with adownflow filter).

Filter A has a housing B and a Flume C (see FIG. 7) formed in the lowerarea of housing B. As illustrated in FIGS. 5 to 7, filter housing B isformed from concrete. However, it will be readily appreciated thathousing B may be formed of any suitable material. Filter A furtherincludes an underdrain system D disposed above the floor E of filter A.The underdrain system E includes a plurality of underdrain blocks 22arranged in rows commonly referred to as laterals. The underdrain blocks22 can be of any desired configuration. Preferably, the underdrainblocks 22 are designed to receive a porous plate used to support filtermedia without the need for support gravel. The underdrain blocks 22include a top wall 21, a bottom wall 23 and a pair of sidewalls 25 and27. Underdrain blocks 22 include a pair of inclined internal walls 29and 31. The underdrain blocks 22 have a hollow cavity extending thelength of the block through which a fluid passes during various phase ofoperation of the filter. The top wall 21 includes a plurality ofopenings (not shown) along the length of the block to allow fluid topass into and out of underdrain blocks 22. Underdrain blocks 22 may havea structure similar to the TRILATERAL® underdrain or the INFINITY®underdrain. For variations on the INFINITY® underdrain see U.S. Pat.Nos. 6,325,931; 6,740,237; 6,569,327; and, 6,989,096 which areincorporated by reference herein in their entirety. It should be notedthat the structure of the underdrain block is not limited to any of theaforementioned underdrains. Rather, the structure of the underdrainblock may be varied as desired.

A given lateral or row in an underdrain system formed in accordance withthis preferred embodiment of the present invention could include one ormore underdrain blocks 22. The number of underdrain blocks 22 in alateral or row of an underdrain system depends at least in part on thesize of the filter and the size of the underdrain blocks 22. Underdrainblocks 22 can vary widely in size. For example, a block can be four feetor less in length to in excess of thirty feet in length.

Preferably, the underdrain blocks 22 rest on a bed of grout 24. Thegrout bed 24 serves two primary functions. First, it aids in levelingthe underdrain blocks 22. Secondly, it forms a seal about flume C. Thisseal serves to isolate flume C so that only the portions of underdrainblocks 22 adjacent flume C experience significant uplift forces causedby fluids moving upwardly from flume C through underdrain blocks 22.Grout strips 33 extend across flume C and provide support for groutabove flume C.

A hold-down assembly F prevents the underdrain blocks from liftingupwardly and separating from the filter floor E. No portion of thehold-down assembly F of this preferred embodiment of the presentinvention is in direct contact with the uppermost surface of underdrainblocks 22. The hold-down assembly F includes a plurality of anchors 26embedded in filter floor E between the laterals. Preferably, anchors 26are all-threads threaded over the entire portion of the anchor. However,any suitable anchor may be used. As seen in FIGS. 6 and 7, hold-downassembly F further includes hold-down clips 28 mounted on each of theanchors 26. The hold-down clips 28 preferably include a plurality ofpins 30 that extend into cavities 32 formed in lugs 34 of the underdrainblocks 22 providing an interlocking connection between underdrain blocks22 and the corresponding hold-down clips 28. As opposed to theinterlocking connection, hold-down clip 28 could merely abut thecorresponding lugs 34 rather than extend into cavities 32.

Preferably, lugs or ribs 34 are formed as one-piece with the sidewallsof the underdrain block 22. However, it will be readily appreciated thatthe lugs or ribs 34 can be formed as a separate piece from theunderdrain blocks 22. The lugs or ribs 34 are preferably disposed atapproximately the midway point between the top wall 21 and the bottomwall 23. However, the location of lugs or ribs 34 may be varied asdesired. Nuts 36 and washers 38 secure hold-down clips 28 to thecorresponding underdrain blocks 22 thereby providing a direct structuraltie to the filter floor E.

The hold-down clips 28 may have one or more pins on each side so that asingle hold-down clip 22 can be directly connected to one or more lugsof adjacent underdrain blocks 22. FIGS. 6 and 7 illustrate one of manypossible configurations. In this configuration, one, of a pair of pins30 of the left most hold-down clip 28 is received in a lug 34 of oneunderdrain block 22 while a second pin of the pair of pins 30 of theleft most hold-down clip 28 is received in a lug 34 of an adjacentunderdrain block 22. Further, two of four pins 30 of the right mosthold-down clip 28 are received in two lugs of an underdrain block 22while the other two of the four pins 30 are received in two lugs of anadjacent underdrain block 22. While the pins 30 are preferably disposedat each of the four corners of the hold-down clips 28, the positioningof the pins 30 and the number of pins may be varied as desired.

Grout 40 may be formed between the laterals to entirely cover hold-downassembly F. In this case, the grout 40 does not act as a hold-down butmerely a seal to protect the components of hold-down assembly F fromcorrosive elements of a filter. This allows the components of hold-downassembly F to be made from less expensive materials. Further, rebar 42may be used to interconnect anchors on opposite sides of flume C toprovide further reinforcement. Where rebar 42 is used, the grout 40 willalso act to prevent lifting of the underdrain blocks 22 and limit thebending stress of underdrain block 22.

FIG. 8

FIG. 8 depicts an embodiment similar to that described in FIGS. 5 to 7and, therefore, only the differences will be described in detail.Similar elements have the same reference characters. The underdrainblocks 44 are of the type disclosed in U.S. Pat. No. 6,740,237 and,therefore, will not be described in detail. Porous plates 46 arepreferably slidably connected to the underdrain blocks 44 in the mannerdisclosed in U.S. Pat. No. 6,740,237. A filler material 48 other thangrout is used to fill the voids between the laterals and provide a seal.The filler material may be a plastic extrusion or compressible materialsuch as polyurethane or other suitable material. The hold-down assemblyof this embodiment is the same as the embodiment disclosed in FIGS. 5 to7.

FIGS. 9 Through 18

FIGS. 9 through 18 depict another preferred embodiment of the presentinvention. The underdrain blocks 22 are of the same structure asdescribed in FIGS. 5 to 7. Hold-down assembly G prevents underdrainblocks 22 from lifting upwardly and separating from the filter floor H.No portion of hold-down assembly G of this preferred embodiment of thepresent invention is in direct contact with the uppermost surface of theunderdrain blocks 22. Hold-down assembly G also includes a plurality ofanchors 52 embedded in filter floor H between the laterals. Preferably,anchors 52 are all-threads threaded over the entire portion of theanchor. However, any suitable anchor may be used. As seen in FIGS. 10and 11, hold-down assembly G further includes an elongated cross member54 connected to and extending between anchors 52 disposed on oppositesides of flume I. Preferably, member 54 has a height greater than itswidth. Member 54 preferably has a first vertically extending segmentthat has a substantially rectangular cross-section as seen for examplein FIG. 14. As seen in FIG. 13, each end of cross-member 54 includesopenings 56 for receiving the corresponding anchor 52. Openings 56 arepreferably elongated as seen in for example FIG. 13. As seen in forexample FIGS. 9 to 13, openings 56 preferably have a fixed size, i.e.,the size of each of the openings 56 is the same when member 54 isdetached from anchors 52 and when member 54 is operably connected toanchors 52. In other words, the size of openings 56 do not vary from apoint prior to operably connecting member 54 to anchors 52 to a point atwhich member 54 is operably connected to anchors 52. The cross member 54further preferably includes an outwardly extending rail 58 having aplurality of hold-down clips 60 slidably mounted thereon. Specifically,hold-down clips 60 preferably include an inwardly extending flange 62that receives rail 58 and allows hold-down clip 60 to slide along rail58. Hence, the position of hold-down clips 60 along the longitudinalaxis of underdrain blocks 22 can be readily varied so that a given clipcan be aligned with a given lug, rib or other corresponding portion ofthe block. Further, flange 62 allows for some relative vertical andlateral movement between hold-down clip 60 and rail 58 to compensate forvariances in the space between underdrain laterals.

Preferably, each hold-down clip 60 includes two pins 64 that arereceived in a cavity of a corresponding lug of underdrain blocks 22.However, it will be readily appreciated that the number of pins on aclip may be varied as desired. Further, the precise manner ofinterconnecting hold-down clips 60 with and the corresponding lugs orother portion of underdrain blocks 22 may be varied as desired. Forexample, an opening passing entirely through the lug could receive oneor more pins of hold-down clips 60. Further, instead of an interlockingconnection, hold-down clips 60 could merely abut the corresponding lugsrather than extend into openings such as cavities formed in the lugs.Further, cross member 54 may be designed to act in concert with thegrout to resist uplift forces or designed to resist applicable upliftforces alone, without the benefit of grout.

FIG. 19

Another preferred embodiment will now be described with reference toFIG. 19. The prior filter systems included an anchor member embedded inthe filter floor such that the anchor would experience primarily tensionforces to prevent uplifting of the underdrain blocks in the underdrainsystems. In this embodiment, all-threads 66 are embedded in filter floorJ in a generally horizontal orientation so that the all-threads 66 andfilter floor J are placed in shear. One of many possible configurationsfor connecting All-threads 66 to underdrain block 72 employs angles 68,all-threads 70, nuts and washers. Specifically, angles 68 connectall-threads 66 to a corresponding all-thread 70 passing throughunderdrain block 72. Nuts and washers may be used to secure all-threads66 to corresponding angles 68. Similarly, nuts and washers may be usedto secure all-threads 70 to underdrain block 72. A gasket 74 may be usedas opposed to grout to seal flume K.

FIGS. 20 and 21

Referring to FIGS. 20 and 21, an alternative hold-down clip 76 isdisclosed. Hold-down clip 76 includes a first section 78 and a secondsection 80 pivotally connected to body 82. This configuration allowssections 78 and 80 to move relative to each other to compensate forvariances in the space between laterals. Each of sections 78 and 80 mayinclude one or more lips 84. Lips 84 may be provided with pins similarto pins 30 that extend into an opening in a corresponding portion of anunderdrain block. While sections 78 and 80 move relative to each otherin a horizontal plane, it will be readily appreciated that theorientation of these sections may be varied to permit movement in avertical plane as well.

While this invention has been described as having a preferred design, itis understood that the preferred design can be further modified oradapted following in general the principles of the invention andincluding but not limited to such departures from the present inventionas come within the known or customary practice in the art to which theinvention pertains. The claims are not limited to the preferredembodiment and have been written to preclude such a narrow constructionusing the principles of claim differentiation.

FIGS. 22 Through 31

With reference to FIGS. 22 to 31, another preferred embodiment of thepresent invention will now be described. Referring to FIGS. 22 and 23, aportion of filter L for filtering water and/or wastewater is illustratedin one of many possible configurations. It should be noted that filter Lcould be a polishing filter or a clarifier. Further, filter L could bean upflow filter, a downflow filter, a bi-flow filter or any combinationthereof (e.g. a filter system formed in accordance with this preferredembodiment of the present invention could include an upflow filter incombination with a downflow filter).

Filter L has a housing and a flume M formed in the lower area of thehousing. The filter housing (only a portion of which is shown in FIGS.22 and 23) can be formed from concrete or other suitable material. Thehousing can be formed in any desired manner and can be entirely enclosedor open at the top. Filter L further includes an underdrain system Ndisposed above floor O of filter L. For purposes of clarity only, onlyone underdrain lateral P is depicted. However, the underdrain systemnormally includes a multitude of laterals positioned in a side-by-sidefashion. Laterals P may include one or more underdrain blocks 90. Theunderdrain blocks 90 can be of any desired configuration. Preferably,the underdrain blocks 90 are designed to receive a porous plate 92 (seeFIG. 31) used to support filter media without the need for supportgravel. Referring to FIG. 31, the underdrain blocks 90 include a topwall 94; a bottom wall 96 and a pair of sidewalls 98 and 100. Underdrainblocks 90 include a pair of inclined internal walls 102 and 104. Theunderdrain blocks 90 have a hollow cavity extending the length of theblock through which a fluid passes during various phases of operation ofthe filter. The top wall 94 includes a plurality of openings (not shown)along the length of the block to allow fluid to pass into and out ofunderdrain blocks 90 Preferably, the openings in the top wall 94 are theonly means through which fluid can pass from the hollow interior of theunderdrain block into the filter bed, i.e., the sidewalls and bottomwalls do not have openings that would let fluid pass from the hollowinterior of the underdrain block to the filter bed. Underdrain blocks 90may have a structure similar to the TRILATERAL® underdrain or theINFINITY® underdrain. For variations on the INFINITY® underdrain seeU.S. Pat. Nos. 6,325,931; 6,740,237; 6,569,327; and, 6,989,096 which areincorporated by reference herein in their entirety. It should be notedthat the structure of the underdrain block is not limited to any of theaforementioned underdrains. Rather, the structure of the underdrainblock may be varied as desired.

A given lateral or row in an underdrain system formed in accordance withthis preferred embodiment of the present invention could include one ormore underdrain blocks 90. The number of underdrain blocks 90 in alateral or row of an underdrain system depends at least in part on thesize of the filter and the size of the underdrain blocks 90. Underdrainblocks 90 can vary widely in size. For example, a block can be four feetor less in length to in excess of thirty feet in length.

Preferably, the underdrain blocks 90 rest on a bed of grout not shown.The grout bed serves two primary functions. First, it aids in levelingthe underdrain blocks 90. Secondly, it forms a seal about flume M. Thisseal serves to isolate flume M so that only the portions of underdrainblocks 90 adjacent flume M experience significant uplift forces causedby fluids moving upwardly from flume M through underdrain blocks 90.Grout strips extend across flume M and provide support for grout aboveflume M. It will be readily appreciated that other flumes configurationsmay be used as opposed to the center flume depicted in FIGS. 22 and 23.

A hold-down assembly Q prevents the underdrain laterals from liftingupwardly and separating from the filter floor O. Preferably, thehold-down assembly Q extends between two adjacent laterals or onelateral and a wall of the filter. As such, an underdrain system formedin accordance with the present invention will likely include a pluralityof hold-down assemblies Q. Further, hold-down assembly Q may extend theentire length of the corresponding laterals or only a portion thereof.Moreover, the hold-down assembly Q may extend substantially parallel tothe corresponding laterals. No portion of the hold-down assembly Q ofthis preferred embodiment of the present invention is in direct contactwith the uppermost surface of underdrain blocks 90.

Referring to FIG. 23, the hold-down assembly Q includes a plurality ofanchors 106 embedded in filter floor O between the laterals. Preferably,anchors 106 are all-threads threaded over the entire portion of theanchor. However, any suitable anchor may be used. As seen in FIGS. 22and 23, hold-down assembly Q further includes a support member 108formed from a plurality of interlocking segments 110.

Because each of the segments 110 is preferably of identicalconstruction, only one will be described in detail hereinafter. Eachsegment 110 includes attachment members 112 and 114 (see FIGS. 24 and25). Preferably, attachment members 112 and 114 take the form of ahollow cylindrical collar. However, the configuration of the attachmentmembers may be varied as desired. Referring to FIG. 25, attachmentmember 112 is disposed adjacent the lowermost edge of segment 110.Attachment member 114 is disposed adjacent the uppermost edge of segment110. This construction allows for adjoining ends of adjacent segments tobe mounted on the same anchor 106 and yet still being substantiallyaligned with each other. For example, attachment member 112 of onesegment would be mounted over a given anchor 90 and the correspondingsegment would extend outwardly from the anchor along a correspondingunderdrain lateral. Attachment member 114 of another segment 110 wouldbe mounted over the same anchor 90 and extend in a direction opposite tothe other segment 110. Because the attachment members 112 and 114 areoffset relative to the longitudinal axis of segments 110, adjoiningsegments 110 can be readily interconnected and substantially aligned toform a support member of any desired length. It will be readilyappreciated that due to the design of segments 110, the segments areinterchangeable. Referring to FIG. 26, segment 110 has a height greaterthan its width. Referring to FIGS. 24, 25, 26 and 31, segments 110 eachinclude a track or rail 116. Preferably, a plurality of hold-downmembers/adjustable anchors 118 are slideably mounted on track 116. Theposition of a given anchor 118 can be readily varied by merely slidingthe anchor along track 116. Preferably, some of the adjustable anchors118 on any given segment engage a portion of one lateral while some ofthe adjustable anchors 118 on the same segment engage a portion of anadjacent lateral. Nuts and washers are mounted on the anchors 90directly above the attachment members 112 and 114 to prevent segment 110from moving upwardly relative to the floor O of the filter.

Referring to FIGS. 27 to 30, one of many possible configurations foradjustable anchors 118 will now be described. The adjustable anchors 118include a base 120, a pair of lugs or protrusions 122 and a pair ofupwardly extending arms 124. As seen in FIG. 31, lugs 122 are receivedin outwardly extending receptacles/lugs 126 of underdrain blocks 90.Arms 124 surround track 116 so that the adjustable anchor 118 canreadily slide on track 116.

FIGS. 32 Through 37

Another preferred embodiment will now be described with reference toFIGS. 32 to 37. This embodiment is similar to the embodiment disclosedin FIGS. 22 to 31 accordingly only the differences will be described indetail. The underdrain laterals R are formed using the well knownINFINITY® underdrain block without the porous plate. However, thisembodiment is in no way limited to an INFINITY® underdrain block.Rather, any suitable underdrain block may be used including those withor without a porous plate.

The hold-down assembly S includes a support member 128 formed from aplurality of segments 130. Segments 130 are similar in construction tosegments 110. Segments 130 extend between adjacent anchors 132. As shownin FIG. 32 and FIG. 37, the hold-down assembly S can extendsubstantially the entire length of the laterals or only a portionthereof. A plurality of adjustable anchors 134 are preferably associatedwith each of segments 130. As seen in FIGS. 35 and 36, adjustableanchors wrap around the corresponding segment 130 and engage an uppersurface of adjacent laterals. Vertical movement of segment 130 isprevented in the same manner that vertical movement of segment 110 isprevented. The position of adjustable anchors 134 can be varied bysimply sliding the same along the corresponding segment 130.

FIGS. 38 Through 40

Another preferred embodiment will now be described with reference toFIGS. 38 to 40. This embodiment is similar to the embodiment disclosedin FIGS. 22 to 31 accordingly only the differences will be described indetail. Hold-down assembly T includes a pair of segments 136 and 138that extend between adjacent anchors 140. Segments 136 and 138 aremoveable relative to each other to compensate for differences betweenadjacent laterals. For example, segment 136 may be offset downwardlyfrom segment 138. Segment 136 includes a pair of cylindrical collars142. Segment 136 further includes a track or rail 144. Preferably, oneor more adjustable anchors 146 are slideably mounted on track 144.Adjustable anchors 146 include one or more downwardly extending lugs 148designed to engage a portion of the corresponding underdrain lateral.Nuts 150 and washers 152 prevent segment 136 from moving upwardlyrelative to the floor of the filter.

Segment 138 includes a pair of cylindrical collars 154. Segment 138further includes a track or rail 156. Preferably, one or more adjustableanchors 158 are slideably mounted on track 156. Adjustable anchors 158include one or more downwardly extending lugs 160 designed to engage aportion of an underdrain lateral adjacent to the underdrain lateralengaged by lug 148. Nuts 150 and washers 152 prevent segment 136 frommoving upwardly relative to the floor of the filter.

While this invention has been described as having a preferred design, itis understood that the preferred design can be further modified oradapted following in general the principles of the invention andincluding but not limited to such departures from the present inventionas come within the known or customary practice in the art to which theinvention pertains. The claims are not limited to the preferredembodiment and have been written to preclude such a narrow constructionusing the principles of claim differentiation.

We claim:
 1. An apparatus for use in a filter system for filtering wateror wastewater, said apparatus comprising: (a) an underdrain lateralhaving at least one underdrain block for supporting at least a portionof a filter bed, said underdrain block having a plurality of exteriorwalls forming a substantially hollow interior; said underdrain blockhaving a plurality of openings through which a fluid passes between saidsubstantially hollow interior of said underdrain block and the filterbed during operation of the filter system; (b) a first anchor spacedfrom a second anchor, said first anchor and said second anchor eachhaving a longitudinal axis that extends substantially perpendicular to alongitudinal axis of said underdrain lateral; (c) an elongated memberhaving a longitudinal axis extending substantially parallel to saidlongitudinal axis of said underdrain lateral, said elongated memberhaving a height greater than its width, said elongated member having afirst opening and a second opening, said first anchor extends throughsaid first opening of said elongated member and said second anchorextends through said second opening of said elongated member, at least aportion of said elongated member extends from said first anchor to saidsecond anchor, said first opening and said second opening permitadjustment of the position of said elongated member along saidlongitudinal axis of said first anchor and said longitudinal axis ofsaid second anchor to locate said elongated member in a desired positionrelative to said underdrain lateral; (d) said first opening and saidsecond opening having a fixed size that does not vary during a processof operably connecting said elongated member to said first anchor andsaid second anchor; and, (e) at least one hold down member engaging saidunderdrain block and said elongated member for holding said underdrainblock down against a floor of said filter system.
 2. An apparatus as setforth in claim 1, wherein: (a) said elongated member is spaced from saidat least one underdrain lateral.
 3. An apparatus as set forth in claim1, wherein: (a) said elongated member is disposed below an upper wall ofsaid underdrain block, said upper wall of said underdrain block having aplurality of openings to permit a fluid to pass through said upper wall.4. An apparatus as set forth in claim 3, wherein: (a) said underdrainblock includes a side wall disposed adjacent said elongated member, alug extends outwardly from said side wall of said underdrain block, anuppermost portion of said elongated member is disposed above said lug,said lug extends only a minor portion of the length of said underdrainblock.
 5. An apparatus as set forth in claim 4, wherein: (a) a flume isdisposed between said first anchor and said second anchor.
 6. Anapparatus as set forth in claim 1, wherein: (a) said underdrain blockincludes an upper wall, said plurality of openings through which a fluidpasses between said substantially hollow interior of said underdrainblock and the filter bed during operation of the filter system areformed in said upper wall of said underdrain block, no portion of saidelongated member is in direct contact with said upper wall of saidunderdrain block.
 7. An apparatus as set forth in claim 1, wherein: (a)said first opening and said second opening of said elongated member areelongated.
 8. An apparatus for use in a filter system for filteringwater or wastewater, said apparatus comprising: (a) first and secondunderdrain laterals, each of said first and second underdrain lateralshaving at least one underdrain block for supporting at least a portionof a filter bed, said at least one underdrain block having an upperwall, a first side wall and a second side wall, said at least oneunderdrain block having a plurality of openings through which a fluidpasses; (b) a first anchor spaced from a second anchor, said firstanchor and said second anchor each having a longitudinal axis thatextends substantially perpendicular to a longitudinal axis of said firstand second underdrain laterals, at least one of said first anchor andsaid second anchor is an all-thread threaded over substantially anentire length of said at least one of said first anchor and said secondanchor; (c) an elongated member having a longitudinal axis extendingsubstantially parallel to said longitudinal axis of said underdrainlateral, said elongated member be operably connected to said firstanchor and said second anchor, said elongated member being configured topermit adjustment of the position of said elongated, member along saidlongitudinal axis of said first anchor and said longitudinal axis ofsaid second anchor to locate said elongated member in a desired positionrelative to said first and second underdrain laterals, said firstanchor, said second anchor and said elongated member being disposedbetween said first underdrain lateral and said second underdrainlateral; (d) grout disposed between said first underdrain lateral andsaid second underdrain lateral, said grout acts with said elongatedmember to resist uplift forces on said first underdrain lateral andsecond underdrain lateral; (e) said elongated member having a firstsegment, a first opening and a second opening, said first opening andsaid second opening having a fixed size such that the size of said firstopening and the size of said second opening is the same when theelongated member is detached from said first anchor and said secondanchor and when the elongated member is operably connected to said firstanchor and said second anchor; and, f) at least one hold down memberengaging said underdrain block and said elongated member for holdingsaid underdrain block down against a floor of said filter system.
 9. Anapparatus as set forth in claim 8, wherein: (a) said first anchor andsaid second anchor are all-threads threaded over substantially theirentire length, a first nut is threaded on said first anchor and a secondnut is threaded on said second anchor to restrict upward movement ofsaid elongated member during operation of the filter.
 10. An apparatusas set forth in claim 8, further comprising a first lug extending from aside of at least one of said underdrain blocks that is engaged by afirst said at least one hold down member.
 11. An apparatus as set forthin claim 10, further comprising a second lug extending from a side of atleast one of said underdrain blocks that is engaged by a second said atleast one hold down member.
 12. An apparatus as set forth in claim 9,wherein: (a) said first anchor extends through a first opening in saidelongated member and said second anchor extends through a second openingin said elongated member.
 13. An apparatus as set forth in claim 12,wherein: (a) said elongated member has a height greater than its width.14. An apparatus as set forth in claim 13, wherein: (a) at least a firstportion of said elongated member completely surrounds said first anchorand at least a second portion of said elongated member completelysurrounds said second anchor.
 15. An apparatus as set forth in claim 14,wherein: (a) said first side wall of at least one underdrain block ofsaid first underdrain lateral is disposed adjacent said first side wallof at least one underdrain block of said second underdrain lateral, eachof said first sidewalls having a plurality of outwardly extending lugs,an uppermost portion of said elongated member is disposed above saidplurality of outwardly extending lugs on each of said first sidewalls.16. An apparatus as set forth in claim 15, wherein: (a) said elongatedmember includes a first segment extending between said first anchor andsaid second anchor, said first segment having a substantiallyrectangular cross-section.
 17. An apparatus as set forth in claim 16,wherein: (a) said first segment extends between said first opening andsaid second opening of said elongated member.